Lung atelectasis is airlessness of the lung tissue caused by the collapse of the alveoli in a limited area (segment, lobe) or throughout the lung. At the same time, the affected lung tissue is excluded from gas exchange, which may be accompanied by signs of respiratory failure: shortness of breath, chest pain, cyanotic tinge of the skin. The presence of atelectasis is established according to auscultation, radiography and CT of the lung. To straighten the lung, therapeutic bronchoscopy, physical therapy, chest massage, anti-inflammatory therapy can be prescribed. In some cases, surgical removal of the atelectated area is required.
J98.1 Pulmonary collapse
Lung atelectasis is an incomplete straightening or total collapse of the lung tissue, leading to a decrease in the respiratory surface and a violation of alveolar ventilation. If the collapse of the alveoli is caused by compression of the lung tissue from the outside, then the term “lung collapse” is usually used in this case. Favorable prerequisites for the development of infectious inflammation, bronchiectasis, fibrosis are created in the collapsed area of the lung tissue, which dictates the need for active tactics in relation to this pathology. In pulmonology, lung atelectasis can be complicated by a variety of lung diseases and injuries; among them, postoperative atelectasis accounts for 10-15%.
Lung atelectasis causes
Lung atelectasis develops as a result of the restriction or impossibility of air entering the alveoli, which may be due to a number of reasons. Congenital atelectasis in newborns most often occurs due to aspiration of meconium, amniotic fluid, mucus, etc. Primary lung atelectasis is characteristic of premature infants who have reduced education or lack surfactant – an antiatelectic factor synthesized by pneumocytes. Less often, the causes of congenital atelectasis are lung malformations, intracranial birth injuries, causing depression of the respiratory center.
In the etiology of acquired lung atelectasis, the following factors are of the greatest importance: blockage of the bronchial lumen, compression of the lung from the outside, reflex mechanisms and allergic reactions. Obturation atelectasis can occur as a result of ingestion of a foreign body into the bronchus, accumulation of a large amount of viscous secretions in its lumen, and endobronchial tumor growth. At the same time, the size of the atelectated area is directly proportional to the caliber of the obstructed bronchus.
The direct causes of compression lung atelectasis can be any volumetric formations of the thoracic cavity that exert pressure on the lung tissue: aortic aneurysm, tumors of the mediastinum and pleura, enlarged lymph nodes in sarcoidosis, lymphogranulomatosis and tuberculosis, etc. However, the most common causes of lung collapse are massive exudative pleurisy, pneumothorax, hemothorax, hemopneumothorax, pyothorax, chylothorax. Postoperative atelectasis often develops after surgical interventions on the lungs and bronchi. As a rule, they are caused by an increase in bronchial secretion and a decrease in the drainage function of the bronchi (poor sputum clearing) against the background of an operating trauma.
Distension lung atelectasis is caused by a violation of the stretching of the lung tissue of the lower pulmonary segments due to the restriction of the respiratory mobility of the diaphragm or the oppression of the respiratory center. Areas of hypopneumatosis can develop in bedridden patients, with diseases accompanied by reflex restriction of inspiration (ascites, peritonitis, pleurisy, etc.), poisoning with barbiturates and other drugs, paralysis of the diaphragm. In some cases, lung atelectasis may occur as a consequence of bronchospasm and edema of the bronchial mucosa in allergic diseases (asthmoid bronchitis, bronchial asthma, etc.).
In the first hours, vasodilation and venous fullness are noted in the atelectated area of the lung, leading to transudation of edematous fluid into the alveoli. There is a decrease in the activity of the enzymes of the epithelium of the alveoli and bronchi and the redox reactions occurring with their participation. The decline of the lung and the increase in negative pressure in the pleural cavity cause the displacement of the mediastinal organs to the affected side. With severe violations of blood and lymph circulation, the development of pulmonary edema is possible. After 2-3 days, signs of inflammation develop in the focus of atelectasis, progressing into atelectatic pneumonia. If it is impossible to straighten the lung for a long time at the site of atelectasis, sclerotic changes begin with the outcome of pneumosclerosis, retention cysts of the bronchi, deforming bronchitis and bronchiectasis.
By origin, lung atelectasis can be primary (congenital) and secondary (acquired). Primary atelectasis is understood as a condition when a newborn child does not have a lung straightening for some reason. In the case of acquired atelectasis, there is a decrease in the lung tissue that previously participated in the act of breathing. These conditions must be distinguished from intrauterine atelectasis (the airless state of the lungs observed in the fetus) and physiological atelectasis (hypoventilation occurring in some healthy people and representing a functional reserve of lung tissue). Both of these conditions are not true lung atelectasis.
Depending on the volume of lung tissue “turned off” from respiration, atelectases are divided into acinous, lobular, segmental, lobular and total. They can be one- and two–sided – the latter are extremely dangerous and can lead to the death of the patient. Taking into account etiopathogenetic factors , lung atelectases are divided into:
- obstructive (obturation, resorption) – associated with a mechanical violation of the patency of the tracheobronchial tree
- compression (collapse of the lung) – caused by compression of the lung tissue from the outside by the accumulation of air, exudate, blood, pus in the pleural cavity
- contractional – caused by compression of the alveoli in the subpleural parts of the lungs by fibrous tissue
- acinar – associated with surfactant deficiency; occur in newborns and adults with respiratory distress syndrome.
In addition, it is possible to meet the division of lung atelectasis into reflex and postoperative, developing acutely and gradually, uncomplicated and complicated, transient and persistent. Three periods are conditionally distinguished in the development of lung atelectasis: 1- the decline of the alveoli and bronchioles; 2 – the phenomena of fullness, transudation and local pulmonary edema; 3 – replacement of functional connective tissue, the formation of pneumosclerosis.
Lung atelectasis symptoms
The brightness of the clinical picture of lung atelectasis depends on the rate of decline and the volume of non-functioning lung tissue. Single segmental atelectasis, micro-atelectasis, and mid-lobe syndrome are often asymptomatic. The most pronounced symptoms are acute atelectasis of the lobe or whole lung. In this case, there is sudden pain in the corresponding half of the chest, paroxysmal shortness of breath, dry cough, cyanosis, arterial hypotension, tachycardia. A sharp increase in respiratory failure can cause death.
Examination of the patient reveals a decrease in the respiratory excursion of the chest and the lag of the affected half during breathing. A shortened or dull percussion sound is detected above the focus of atelectasis, breathing is not listened to or sharply weakened. With the gradual shutdown of the lung tissue from ventilation, the symptoms are less pronounced. However, subsequently, atelectatic pneumonia may develop in the area of hypopneumatosis. An increase in body temperature, the appearance of cough with sputum, an increase in symptoms of intoxication indicates the addition of inflammatory changes. In this case, lung atelectasis may be complicated by the development of abscessing pneumonia or even lung abscess.
The basis of instrumental diagnosis of lung atelectasis is X-ray studies, primarily lung radiography in direct and lateral projections. The X-ray picture of atelectasis is characterized by homogeneous shading of the corresponding pulmonary field, displacement of the mediastinum towards atelectasis (in case of collapse of the lung – to the healthy side), high position of the diaphragm dome on the affected side, increased airiness of the opposite lung. During lung x-ray on inhalation, the mediastinal organs shift towards the sleeping lung, on exhalation and when coughing – towards a healthy lung. In doubtful cases, the radiography data are clarified using CT of the lungs.
Bronchoscopy is informative to find out the causes of obstructive pulmonary atelectasis. With long-term atelectasis, bronchography and angiopulmonography are performed to assess the extent of the lesion. Radiopaque examination of the bronchial tree reveals a decrease in the area of the atelectated lung and deformation of the bronchi. According to the APG data, it is possible to judge the state of the pulmonary parenchyma and the depth of its lesion. The study of the gas composition of the blood reveals a significant decrease in the partial pressure of oxygen. As part of the differential diagnosis, agenesis and hypoplasia of the lung, interstitial pleurisy, relaxation of the diaphragm, diaphragmatic hernia, lung cyst, mediastinal tumors, croup pneumonia, lung cirrhosis, hemothorax, etc. are excluded.
Lung atelectasis treatment
Detection of lung atelectasis requires an active, active tactics from a doctor (neonatologist, pulmonologist, thoracic surgeon, traumatologist). Newborns with primary lung atelectasis are sucked out of the contents of the respiratory tract with a rubber catheter in the first minutes of life, if necessary, tracheal intubation and lung straightening.
In case of obturation atelectasis caused by a foreign body of the bronchus, it is necessary to perform therapeutic and diagnostic bronchoscopy to extract it. Endoscopic sanitation of the bronchial tree (bronchoalveolar lavage) is necessary if the collapse of the lung is caused by the accumulation of difficult-to-cough secretions. In order to eliminate postoperative lung atelectasis, tracheal aspiration, percussion chest massage, respiratory gymnastics, postural drainage, inhalations with broncholytic and enzyme preparations are indicated. With lung atelectasis of any etiology, it is necessary to prescribe preventive anti-inflammatory therapy.
In case of lung collapse caused by the presence of air, exudate, blood and other pathological contents in the pleural cavity, urgent thoracocentesis or drainage of the pleural cavity is indicated. In the case of long-term existence of atelectasis, the impossibility of straightening the lung by conservative methods, the formation of bronchiectasis, the question of resection of the affected area of the lung is raised.
Prognosis and prevention
The success of straightening the lung directly depends on the cause of atelectasis and the timing of the start of treatment. With the complete elimination of the cause in the first 2-3 days, the prognosis for the complete morphological restoration of the lung area is favorable. At later periods of lung expansion, it is impossible to exclude the development of secondary changes in the dormant area. Massive or rapidly developed atelectasis can lead to death. For the prevention of lung atelectasis, it is important to prevent aspiration of foreign bodies and gastric contents, timely elimination of the causes of external compression of lung tissue, maintenance of airway patency. In the postoperative period, early activation of patients, adequate anesthesia, exercise therapy, active coughing of bronchial secretions, if necessary, rehabilitation of the tracheobronchial tree is indicated.
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